Molar pregnancy Flashcards
What is gestational trophoblastic disease (GTD)?
used to describe group of pregnancy-related tumours; split into pre-malignant and malignant conditions
What are the 2 groups of types of gestational trophoblastic disease?
- Pre-malignant conditions e.g. partial molar pregnancy and complete molar pregnancy
- Malignant conditions e.g. invasive mole, choriocarcinoma, placental trophoblastic site tumour and epithelioid trophoblastic tumour
Of the 2 types of gestational trophoblastic disease, which type is more common?
Pre-malignant conditions more common than malignant conditions
What are 2 types of pre-malignant GTD?
- Partial molar pregnancy
- Complete molar pregnancy
What are 4 malignant forms of GTD?
- Invasive mole
- Choriocarcinoma
- Placental trophoblastic site tumour
- Epithelioid trophoblastic tumour
What, broadly speaking, is the cause of molar pregnancies?
abnormality in chromosomal number during fertilisation
What is the cause of partial molar pregnancy?
one ovum with 23 chromosomes is fertilised by two sperm, each with 23 chromosomes - results in triploidy (cells with 69 chromosomes)
If a partial mole exists with a viable fetus, what is going on genetically in the cells of the fetus and placenta?
the fetus and placenta are usually triploid, however mosaicism can exist where the fetus has a normal karyotype and triploidy is confined to the placenta
What is the cause of complete molar pregnancy?
one ovum without any chromosomes is fertilised by one sperm which duplicates, or (less commonly) two different sperm, leading to 46 chromosomes of paternal origin alone
How do invasive moles differ from benign molar tumours?
they invade into the uterine myometrium and disseminate around the body. benign molar pregnancy can become malignant
What is choriocarcinoma?
malignancy of the trophoblastic cells of the placenta, commonly co-exists with a molar pregnancy
Where does a choriocarcinoma characteristically metastasise to?
lungs
What is a placental site trophoblastic tumours?
malignancy of the intermediate trophoblasts which are normally responsible for anchoring the placenta to the uterus
What are 3 things that a placental site trophoblastic tumours can arise from and which is most common?
- Normal pregnancy → most common
- Molar pregnancy
- Miscarriage
What is an epithelioid trophoblastic tumour?
malignancy of the trophoblastic placental cells, which can be very difficult to distinguish from choriocarcinoma
What type of cancer does an epithelioid trophoblastic tumour mimic the cytological features of?
squamous cell carcinoma
What are 4 major risk factors for gestational trophoblastic disease?
- Maternal age <20 or >35
- Previous gestational trophoblastic disease (risk is not decreased by a change of partner)
- Previous miscarriage
- Use of oral contraceptive pill
Is the risk of gestational trophoblastic disease that is associated with previous GTD decreased by a change of partner?
no
What are 5 earlier clinical features of molar pregnancies?
- Vaginal bleeding
- Abdominal pain in early pregnancy
- Larger uterus than expected for gestation
- Soft, boggy uterus
- Molar vesicles can occasionally shed per vagina
If molar pregnancy is undiagnosed, what are 3 late clinical features?
- Hyperemesis
- Hyperthyroidism
- Anaemia
Why is excessive hyperemesis thought to occur with molar pregnancy?
increased titre of beta hCG which is thought to be linked to nausea in pregnancy
What causes hyperthyroidism in late molar pregnancy?
gestational thyrotoxicosis due to stimulation of thyroid by high HCG levels (acts like TSH)
What are the 4 most common investigations in the assessment of suspected gestational trophoblastic disease?
- Urine beta-hCG
- Blood beta-hCG leels
- Ultrasound scan
- Histological examination of the products of conception post-treatment
When will the urine beta-hCG remain positive following delivery?
for a number of weeks (usually say by 4 weeks it should be negative)
